Stress Corrosion Cracking of Mild and Low Alloy Steels in CO-CO2-H2O Environments

This paper is related to the new stress corrosion cracking phenomenon of mild and low alloy steels in a CO/CO2 environment. The incidents of cracking are described and these were reproduced by laboratory tests. The results obtained are as follows: (1) No stress corrosion cracking of mild steel was found to occur in water containing just CO or CO2. (2) The transgranular stress corrosion cracking occurred only in CO/CO2 environment with water. (3) Stress corrosion cracking occurred in a wide range of CO/CO2 ratios in water. (4) The susceptibility to stress corrosion cracking of mild steel decreases with increasing temperature. (5) No stress corrosion cracking was found to occur on 18Cr-10Ni stainless steel. (6) From the study of electrochemical measurements, the mechanism has been proposed that this form of cracking is stress corrosion cracking rather than hydrogen embrittlement. (7) Prevention of stress corrosion cracking in these environments is discussed.